Collapsible plunger head



F. J. RIZZITANO COLLAPSIBLE PLUNGER HEAD Aug. 18, 1959 2 Sheets-Sheet 1 Filed May 28, 1957 www l//// W 1NVENTOR, FBT-iunuu .l Rizzilunn Www QL'TJZQA F. .1.RlzzlTANo 2,900,075

CGLLAPSIBLE PLUNGER HEAD Aug. 18, 1959 Filed May 28, 1957 2 Sheets-Sheet 2 @Ill n un N :lllW

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INVENTOR)' CLLAPSIBLE PLUNGER HEAD Fortunato J. Rizzitano, Framingham, Mass., assignor to the United States of America as represented by the Secretary of the Army Application May 28, 1957, Serial No. 662,301

3 Claims. (Cl. 207-6) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to apparatus for extruding hollow cylinders and in particular to apparatus :for extruding by piercing punch and die means.

There are some materials which are not readily adapted to extrusion by the piercing punches lwhich have been provided in the art hereinbefore because of the chemical and/or physical afinity of the extrusion material for the material of the punch. Whereby, when the punch is withdrawn from the hole formed thereby in the extrusion, seizure or galling frequently occurs causing either complete loss Vof the punch or considerable damage to the punch or the extrusion.

One of suchvmaterials is titanium, a material having very desirable characteristics but which is diflicult to Work with conventional tools and by usual methods be-4 cause of its affinity for other materials whereby galling or seizure results from the frictional contact thereof with other metals, as in the art of extrusion.

Because of this ainity, it has been difiicult or impossible in the past to form titanium cylinders with dead end holes having constant inside and outside diameters by backward extrusion without large draft angles as the punch would be seized during the extraction thereof and, thus, have to be drilled out at a considerable loss. it has also been difficult 'to extrude cylinders having inner holes of constant diameter all the way therethrough because any hesitation during the act of extrusion causes seizure as titanium loses heat very rapidly and, consequently, the punch has to be machined out of the extrusion.

lt is, therefore, an object of this invention to provide a piercing punch which retains its desired configurationv during the power or extruding stroke but which is collapsible during the retraction stroke whereby galling or seizure is prevented between the punch and the extrusion. l

it is another object of this invention to provide a piercing punch which is separable into smaller units when retracted from the hole formed thereby in an extraction.

lt is a further object of this invention to provide a split die which is separable after extrusion to prevent frictional Contact between the die and the extrusion during the withdrawal thereof.

lt is a still further object of this invention to vprovide a container with a tapered recessfor receiving a cylindrical die which is tapered on the outsideV to mate with the taper of the recess in the container and is provided with an axial hole of desired constant diameter and which is longitudinally divided into two halves so that when the die is inserted into the container the two halves are force together to form an integral sleeve and, when the container is lifted from the die, the die is separable for easy removal of the extrusion.

It is still another object of this invention to provide tetes Patent ice die and punch means for extruding titanium which completely eliminates the use of tapered piercing punches and all draft angles required in conventional deep forgings and backward extrusions.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear yfrom a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a side view of the extrusion apparatus mounted to a press;

Fig. 2 is an enlarged cross-sectional side View showing the punch moved into a billet to form a hollow cylindrical extrusion;

Fig. 3 is a view similar to Fig. 2 but showing the punch separated during the retraction stroke;

Fig. 4 is an enlarged cross-sectional side View of the die with the die holder raised therefrom to show the separation of the divided halves of the die when the die holder is raised therefrom;

' Fig. 5 is an lenlarged end view of the punch in assembled relationship;

Fig. 6 is a view similar to Fig. 5 but showing the segments separated from the punch; and

Fig. 7 is an enlarged exploded perspective view of the punch assembly.

Shown in the figures is an extruding apparatus including a'hollow die 12 for receiving a preheated cylindrical lbillet 14, which is to be extruded into a tube, and a Apunch 16, which is actuatable by press 18 against the billet to extrude the material thereof rearwardly between the outer periphery of the punch and the inner periphery of the die.

Die 12 is in eect a cylindrical sleeve which is split longitudinally in half to form two Sernicylindrical portions 20 and which is provided with a hole 22 of constant diameter axially therethrough. The outer diameter of die 12 is tapered approximately two degrees inwardly from the bottom to the top end.

Die 12 is receivable in a die holder '24 which is removably mounted to the base of press 18. Holder 24 is provided wtih a conical recess 26 which receives die 12 upwardly thereinto and which is tapered to mate with the outside of the die. Whereby, when die 12 is install-ed in holder 24, the portions 26 are cammed firmly together to forman integral sleeve and, when the holder is lifted upwardly from die 12 by hoistingjmeans (not shown), space is provided therebetween, permitin place in holder 24.

Punch 16 includes a head 30 and a stem portion 32 which extends axially from the upper end thereof to be received by a mandrel mounted to press 1S. Head 30 is substantially domelike in conguration. The greater portion of the outside surface of head 30 is removed by a pair of similar and diametrically-opposed cutout sections 34, to be more specically described hereinafter, and removable segments 36 of substantially similar configuration are installed therein. Extending axially from the end of head 30 is a cylindrical lug portion 33 the circular wall of which is arcuately blended to the surrounding area of the head and to a spherical end portion 39 which terminates such lug portion. v

The sections 34 are cut symmetrically from head portion 30 to form a diametrical tongue portion 40. Each of such sections 34 is formed by a chordally disposed inner wall 42, which inclines outwardly and upwardly from the bottom end of head 30 to a position spaced vfrom the upper end thereof, and by an end wall 44, which extends outwardly from the end of wall 42 at a 90 angle,

'LJ The walls 42 intersect the end of head 30 at the arcuate junction of the circular wall `of lug portion 38 with such head so that such walls 42 include a section of such arcuate blend for a purpose to -be explained hereinafter. The portion of head 30 above end wall 44 is reduced approximately .060 inch in cross-section by diametricallyopposed clearance cuts 46, to provide a clearance between the head, when rotated 90 degrees, and the extrusion during the retraction of the punch as hereinafter noted. Projecting from the upper portion of each` of the walls 42 and disposed symmetrically thereto, is a rectangular key portion 48 which is slidingly received in a mating keyway 50 provided in the abutting side of the respective one of the segments 36 whereby the segments may be slidingly removed from the head in a longitudinal direction but are restrained from lateral movement respective to such head.

Each of the segments 36, when assembled to head 30, is iirmly secured against upper movement relative to such head by the engagement of the top side thereof with abutting end wall 44 and is releasably secured against downward displacement by a shear pin 52 which is assembled to head 30 so as to extend outwardly from the inner wall 42 and be received in a mating hole in such segment. The shear pins 52 are fabricated from a material which is easily sheared when heated, such as brass.

As has been noted Vhereinbefore, the segments 36v have substantially the same configuration as the sections 34 into which they fit. However, in order to have the frictional contact between punch 16 and the extruding material borne where possible by the segments 36, the radii ofthe segments are gradually increased from the lower portion thereof, where the radii are similar to that of head 30 in the same transverse section, toward the top so that the radii of the top portions are slightly larger than that of the top portion'of head 30lv above tongue portion 40. Consequently, the top of the segments 36 project slightly from head 30 and thereby the segments extend the hole formed in billet 14 to the desired diameter in advance of the integral portion of the head, which has an advantage that will be explained hereinafter. Also, the portions of the blending arcuation between lug portion 38 and head 30 removed by the sections 34 are not replaced by the segments 36. Whereb-y, when punch 16 is pressed into billet 14, the material will ilow from end portion 39 over the divisions between tongue portion 40 and the segments 36 so as not to be forced between such tongue portion and segments and cause separation thereof.

Thus, to extrude billet 14 into a hollow cylinder, a die 12 having the desired inside diameter, which will determi-ne the outside diameter of the extruded cylinder, is mounted to press 18 and a mating die holder 24 installed thereover. Die 12 and holder 24 are then mounted together .by the locking means 28 and a punch 16 of desired outside` diameter, which will determine'thet inside v'diameter of the extrusion, installed in presslandaxially aligned `with the die.

Billet 14 is preheated to a suitable temperaturelto facilitate the flow of the material `during thev extiusion and placed in 1diei12. Press 18.is immediately actuated' to move punch 16zinto billet 14 and start the extrusion wherebythe material displaced by thepunch flows up.2 wardly between the punch'and ydie =12 to form a `hollow cylinder.

As has been explained hereinbefore; the ysegments36 are releasably held in Vassembled relationshipto head 30 prior to insertion intov 'billet 14 by the shear .pi'nsf52. During the movement of punch 16 `through'zbillet 14, the segments 36 are held integral with head 30hy theangu-v larity; of theV endwalls 44 and themating Atop sides of the segments whereby the upper pressure against .the bot-V tom of the segments camsthe top of suchzsegments inwardly `into irm1contact with the innery walls 42. The corrieV conlgurationsrof theoutside .of segments 36..also,

serve to cam the segments into firm contact with the inner walls 42 when punch. 16 is moved through billet 14. Further, as has been noted hereinbefore, by the arcuate 'blending of lug portion 35 with head 30 being interrupted by the sections 34, the material of billet 14 flows from the lug portion to the segments 36 over the division thereofwith head 3u so as not to cause separation thereof. Moreover, the segments 36 are secured against lateral displacement through the cooperation of key 48 with the keyway 50.

When punch 16 has been moved suciently into billet 14 to form the desired extrusion, the operation of press 118 is reversed to move the punch upwardly. If there is suicient frictional resistance to upward movement of the punch .by the engagement thereof with the extrusion to cause galling and damage to the punch or the extrusion, the shear pins 52 will be sheared to release the segments 36 ,and thereby the greater area of contact between the punch and the extrusion. Further upward movement of punch 16 will release the radial pressure of the segments 36zagainst the extrusion because of the inclinations of the inner walls 42. Whereby, punch 16 is freed to be rotated so that tongue portion 40 will align with the larger diameter portion of the extruded hole formed by thesegments 36 andbecause the diameter of head 30 abovethe sections 34 is reduced by the clearance cuts 46, the punch is freed from Contact with the extrusion during further retraction.

When punch 16 is withdrawn from the extruded cylinder, holder 24 is lifted from die 12 after being unlocked therefrom whereby the portions are separable to free such cylinder from the die without sliding contact therebetween whieh might cause galling.

Fromthe foregoing, it is clearly apparent that there is herein provided an extrusion apparatus which is ideally suited to the extrusion of materials having affinity for the metals of the extruding apparatus by the punch being separable during the retraction stroke and formed to prevent contact with the extruded cylinder when retracted and -by the die being dividably held together.

Although "a particular embodiment of the invention has beeny described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such' variations.

I claim:

1. A punch mountable to a reversible press for insertion into a billet for displacing the material thereof to form a hole therein, said punch including in combination a head, an integral tongue portion, segments disposed for` assembly to said head to complement said tongue portion in forming the hol-e, said segments being held in aslsembled position on said tongue portion by shear pins before the punch contacts the billet, and cooperating cam surfaces disposed on said head and in said segments for firmly engaging said segments to said head in assembled relationship when said punch is pressed into the billet and vfor reducing the radial pressure of said segments against the wall of the hole when said punch is reversibly moved therein.

2. A punch mountable to a reversible press for insertion into a billet to displacingly form a hole therein, said punch including in combination a domelike head, a pair of recessed sections in said head formed -by chordally disposed inner walls extending upwardly and outwardly from Ithe end of said head and end walls extending out- 'wardly from the upper ends of said inner walls, a tongue portion formed by said sections, a clearance cut provided in said head above each of said sections to provide space -between said head and the hole when said punch is rotated 90 degrees after withdrawal from a linished workpiece, and segments cammingly engaged with said inner and end Walls -for rmly seating said segments in said Section5 Wh@ ,Saidpunch is pressed into the billet, said segments Ibeing disposed to complement said tongue por- References Cited in the file of this patent tion in forming the hole, said segments heilt-,1g hlelld in as- UNITED STATES PATENTS sembled position on said tongue portion y s ear pins before the punch contacts the billet. l 'gasket 1 any 3. The combination as recited in claim 2 and including 5 2024286 Harss et a D ay 17, 1935 a cylindrical lug portion extending axially from said head 2,261,304 s anksef lc- 4, 1941 and of suicient diameter to join with the adjacent ends 2'700906 Alr ISV l, 1955 of said inner walls on said head, and a spherical end 2806596 D t--a --g 7 1957 portion terminating said lug portion Afor owing the ma- 1 0 s e eP terial of the billet away from the wall of said lug portion l0 FOREIGN PATENTS and the divisions between Said tongue portion and said 880,040 France Dec. 10 1942 segments during insertion of the punch into the billet. 

